>   You sure are.  I've been *trying* to tell you the answer, and you are
> *determined* to ignore it!  One more try:

This is hard for me. Apparently not for you. I apologize for my stupidity.
I take on hard projects, so that I learn something doing them. This one has
been rather a stretch in some regards.

>   To evaluate arctangent, you restrict it to an octant by making signs
> match and exchanging X and Y to constrain the ratio Y/X or X/Y to be
> positive, less than or equal to one.  Then you use either a lookup
> table, a sparse lookup table with interpolation, or a Taylor series (or
> CORDIC).  All these use scaled integer maths.

I follow, I think, I will try to code this.

>   That's right.  Use the book, Luke!  It says Arctangent, it *means*
> arctangent.

I get confused when another book uses csc (I assume cosecant) in the same
position, same formula. My formal math education stopped about mid-high
school, and effectively at the 8th grade, (long ugly story, mistakes I made,
teachers that should have been security guards at a donut factory..)